Arc-light electrode.



I. LADOFF.

' Anc LIGHT ELEGTBODB.

APPLIOATIOK FILED TURB 1,1907.

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are 7017110022714 i J'aZz Patented May 7, 1912.

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UNITED sTATEs PATENT oEEI'oE.

ISADOB LADOFF, F CLEVELAND, OHIO, ASSIG-NOB OFiTHIRTY A PHILIP C. PECK,0F NEW'YORK, N. Y.,

`oNE-HUNDmin'rHs To ABC-LIGHT ELEQTBDDE.

To all 'whom t may concern.'

Be it known that I, IsADoR LADoFF, a citizen of the United States, and aresident of the city of Cleveland, county of Cuyahoga, and State ofOhio, have invented certain new and useful Improvements in Arc-LightElectrodes, of which the following is a speciiicat-ion, reference beinghad to the accompanying drawings, in which- Figure 1 is a perspectiveview of one of my pencils and Fig. 2, a central longitudinal section ofFig. 1.

My present improvements relate particularly to arc lights for metallic,or essentially metallic encils, that is to say pencils composed of)metal, or preponderatingly of metal, and a principal object of myinvention is to adapt such pencils to produce, readily, in thealternating current, well defined, long, quiet, and .exceptionallyluminous arcs, though my said pencils are also well adapted to be usedin a continuous current.

The opinion has, I believe, been hitherto universal that the alternatingcurrent cannot, with practical and industrial success, be maintainedbetween non-carbon pencils. I have discovered that the aforesaid objectsof my present invention can be attained and metallic pencilssuccessfully usedl in the alternating current by bringing salts into thepresence of the molten metal at the upper surface of such pencils insuch current, whibh I secure by imparting to such pencils a cylindricalform, i. e., a central longitudinal bore and filling the latter withsalts of alkaline, or electropositive metals, such as on the one handsodium or otassium salts, preferably potassium fluorld, or on the otherhand salts of cacsium, rubidium, calcium.

The pencils may be made of the metal desired in any convenient way; theyare then drilled or otherwise treated, to produce the bore into which ispacked the coring of salts, as aforesaid. Those skilled in the art willreadily understandhow, in the case of different metals, to determine thevbestv proportions of core and pencil relatively to each other; also howbest in each Specification of Letters Patent.

Application led J'une 1, 1907. Serial Ko. 376,868.

Patented May 7, 1912.

case to' produce the hollow pencils and insert the coring. For example:I have produced what may be termed an essentially metallic pencil asfollows: I mixed together with 'oxid of titanium enough pulverizedmagnetite to insure presence in the pencil produced as hereinafterdescribed of at least 60 parts metallic iron and oXid of titanium,

binder, a s all proportion of water, sufficient to im art to the powderadhesion and placticity. I then squirted and molded the plastic massinto the forms required for the pencils, these being cylinders of abouteight (8) inches long' and one-half (5) inchv diameter. After drying inthe open air for several hours, the pencils were further dried in anoven at a temperature of about 200 degrees centigrade for somefortyeight hours. They were then packed in carbon, and subjected forabout eight (8) hours to a temperature of from 1200 degrees to 1500degrees centigrade, the magnetite being thus substantially reduced tometallic iron, and the finished pencils composed preponderatingly ofiron, the pencils having a diameter'of about 92' and a bore of 0.185inch in diameter. This bore was packed full of potassium luorid. Inarcing, the described pencils were used as cathode and anode. Analternating current being turned on, 4 amperes and 80 to 90 volts dropacross the arc, the resulting arc was readily maintained indefinitely.It was of superior luminosity, well defined, long and quiet. Of coursethe said metallic pencils may be prepared in any other convenientmanner, the essential point being to provide them with a core of saltsas stated.

I am aware that carbon pencils, mineralized carbon pencils, and the likehave been previously cored, also, that salts have been incorporated intosuch pencils, and therefore do not broadly claim coring, or theintroducti'on of salts into pencils generally.

What I claim as new and desire to secure by Letters Patent is thefollowingz- 1. A metallic arc light pencil comprlsmg a bore containingpotassium iuorid.

2. An essentially metallic arc light pencil 40 parts. 0 the mixture Iadded as a composed preponderetingl)7 of iron and 5. An arc-light pencilcomposed prepon- 10 comprising a bore contaming potassium deratingly ofiron in elemental state and fuorid. comprising a central longitudinalbore con- 3. A metallicdar light pencilcom rising taining a salt of analkaline met-a1.

5 a core com ose o potassium uorl 4. An arg-light pencil composedprepon- ISADOR LADOFF deratingly of metal in elemental state andWitnesses: comprismg a 'central lon 'tudinal bore con- F. W. SINRAM,taimng a, salt of an alkalme metal. R. P. MEQUIILET.

